Method of controlling the rimming of ingots



z s ww Aug. 30,1949. J. s. STANIER ET AL METHOD OF CONTROLLING THE RIMMING OF INGOTS Filed Aug. 1, 1946 QN %N x @N M @m T W m 1. m

Patented Aug. 30, 1949 METHOD OF CONTROLLING THE RIMMING F INGOTS John S. Stanler and Ernest B. Plott, Youngstown,

Ohio, assignorsto The Youngstown Sheet and Tube Company, Youngstown, Ohio, a corporation of Ohio Application August 1, 1946, Serial No. 687,570

6 Claims.

This invention relates to the casting of ingots from molten metal and, in particular, to the control of the rimming of molten steel while cooling and freezing to solid form in ingot molds.

Steel as now produced commercially is classified according to its degree of effervescent action'when cast into ingot molds as rimming, semi-killed, or killed (The Making, Shaping and Treating of Steel by Camp 8: Francis, th ed., 1940, p. 356).

Steel of each classification has well recognized advantages and disadvantages. An ingot of killed steel, for example, has a high degree of uniformity in metallurgical composition but does not have the so-called "skin" characteristic of an ingot of rimming steel. This skin is desirable for the reason that it causes the final product to exhibit fewer surface defects than are present in products made of killed steel. Rimmed steel is also desirable for drawing stock and for its good welding properties. Conversely, a rimmed ingot has a non-uniform composition in the top portion. This requires a substantial portion at the top of the ingot to be cropped and scrapped. The upper one-third of the ingot remaining after cropping, furthermore, is not satisfactory for deep-drawing stock and must be scrapped or used for making other products.

We have invented a method of controlling the rimming action of steel in the ingot mold so as to produce ingots of rimmed steel having the high degree of uniformity throughout the' top portion makes possible the use of the upper one-third of the ingot left after cropping, for. making deepdrawing stock. In a preferred practice of our invention, we suspend an insert of steel, conveniently a piece of plate, in the top of the ingot mold at a level such that it becomes more or less submerged in the bath of molten'steel when poured into the mold to the desired final depth. Steel having full rimming properties is then poured into the mold. The insert is partially fused by the heat of the molten metal and becomes integrally united with the ingot as itfreezes. Its presence controls and limits the rimming action so that it is terminated before objectionable nonuniformity in the composition of the top of the ingot has'been produced.

A complete understanding of the invention may be gained from the following detailed description drawings illustrating the preferred practice diagrammatically. In the drawings.

Figure 1 is a'plan view of an ingot mold having one form of insert disposed therein;

Figure 2 is a vertical section through the mold and ingot cast therein;

Figures 3 and 4 are views similar to Figures 1 and 2, respectively, showing a modified form of insert; and

Figures 5 and 6 are also views similar to Figures 1 and 2, respectively, showing a still further modification.

Referring in detail to the drawings, an ingot mold i0 is disposed on a stool II. An insert I2 is suspended in the upper portion of the mold. The insert has a shackle l3 secured thereto through which is passed a supporting crossbar I4 which extends the width of the mold and rests on the upper edge thereof. I

The insert l2, as shown, is a piece of steel plate and has a composition similar to that of the steel to be poured into the mold I 0 to form'an ingot. The insert should weigh from .2 to .5% of the weight of the ingot, if it is desired to produce strip having the best drawing properties from the ingot. For other products, such as patent leveled sheets or tin plate, where flatness and temper are more important than cleanliness and drawing properties, the weight of the insert should be somewhat greater. In a particular instance, the insert used was a triangle formed from plate, measuring 20" along its base with an altitude of about 17". With the insert in place in the mold, molten steel having full rimming properties is poured into the mold substantially to the level of the top of the insert as indicated at l5, forming an ingot l6. While we prefer to suspend the insert in the mold before pouring the ingot, the insert may alterbeing to prevent continuation of rimming to the point where it causes objectionable non-uniform- .ity in the upper portion of the ingot. The greater the size of the insert, the greater the suppressing effect on the rimming action. No special surface preparation of the insert is necessary. The presence on the insert of the oxide or scale normally resulting from hot rolling is in no way detrimental and explanation which referto the accompanying to the process since it melts immediately and is cropped in the usual manner.

ever, that our invention increased the overall .yield of the ingot by from 2 to 3% because the area of non-uniformity did not extend downwardthe triangle l2.

By suspending the insert in the mold before pouring the molten steel or placing it in the bath as soon as the pouring is completed, the insert is partially fused and finally becomes integrally united with the ingot as the latter freezes. During cooling, inclusions such as sulphur, phospho rus, oxides and silicates move upwardly and inwardly, eventually striking the converging sides regions I! adjacent the top of the ingot. The insert, by reducing the amount of rimming which occurs, cuts down the rimming time.

In a specific example of the practice accordin 4 ticned. The ability to use the top third of the ingot for high-grade deep-drawingsteel obvigiusly represents a substantial increase in the net eld.

While the invention has been described with particular reference to rimming steel, it may also be used in pouring ingot iron which is cast in molds similar to those used for steel ingots.

Although we have described and illustrated but a preferred practice of the invention with slight of the insert which deflect them laterally into to our invention. a heat of steel was poured having the following composition: carbon .07%: manganese 37%; phosphorus .00795; sulphur .022%; and the balance substantially iron. An insert such as that shown at I! was used, composed of steel plate of about the same composition. when the ingot had cooled sufflciently, the mold was stripped therefrom and the ingot It was found, howly as far from the top of the ingot as in the case of ingots poured without the insert. It was thus possible to. take a shorter crop from the top of the ingot.

formed satisfactorily in drawing dies, showing a breakage of only 1.03% in making automobile fenders. This figure was better than that for the stock produced in the lower two-thirds which showed a breakage of 1.8%. This is in contrast with. normal rimmed steel in which the breakage 'of the stock produced from the top third of the ingot is much greater than that encountered in the stock produced from the lower two-thirds.

Other forms of inserts may be used as well as Figures 3 and 4 show an insert l8 of rectangular shape which has generally the same efi'ect, diverting inclusions to laterally spaced regions II. Figures 5 and 6 show a further modification in which the inserts are cylindrical members I 9 disposed side-by-side, the central member being longer than the side members.

Our invention has the advantage that it makes possible the casting of an ingot having a skin characteristic of rimmed steel but with a uniformity similar to that of an ingot of killed steel. The use of full-rimming steel insures the minimum of surface defects and a maximum of cleanliness and ductility. These characteristics are desirable particularly for stock intended for drawing and forming operations. Rimmed steel is also desirable because of its welding qualities. Our invention combines the advantages of rimmed and semi-killed steel and avoids the disadvantages of killed steel.

A further advantage of the invention is that no special surface preparation of the insert is necessary. The insert, furthermore, may be placed in the mold before pouring or immediately thereafter. No measured wait is necessary with the possibility of varying the effects on the freezing of the ingot.

The increased yield and the possibility of using the top third of the ingot for drawing stock are further advantages which have already been menmodifications, it will be understood that changes in the procedure disclosed may be made without departing from the spirit of the invention or the scope of the appended claims.

We claimt 1. In a method of controlling the rimming of -an ingot, the steps of pouring molten ferrous rimming metal'into an ingot mold and not substantially later than immediately after the conclusion of pouring placing in the upper portion wardly and to reduce and limit the normal rimming action.

2. In a method of controlling the rimming of an ingot, the steps of pouring molten ferrous rimming metal into an ingot mold and immediately after the conclusion of pouring placing in the upper portion only of the mold and fixedly positioning relatively to the mold an insert of solid ferrous metal which partially fuses into the molten metal and serves to move inclusions upwardly and outwardly and to reduce and limit the normal rimming action.

3. In a method of controlling the rimming of an ingot, the steps of placing in the upper portion only of an ingot mold and fixedly position- 4 ing relatively to the mold an insert of solid ferrous metal and thereafter pouring molten ferrous rimming metal into the mold, the insert partially fusing into the molten metal and serving to move inclusions upwardly and outwardly and to reduce and limit the normal rimming action.

4. In a method of controlling the rimming of an ingot, the steps of pouring molten ferrous rimming metal into an inset mold and not substantially later than immediately after the conclusion of pouring placing in the upper po tion only of the mold and fixedly positioning relatively to the mold a plate of solid ferrous metal which partially fuses into the molten metal and serves to move inclusions upwardly and outwardly and to reduce and limit the normal rimming action.

5. In a method of controlling the rimming of an ingot, the steps of pouring molten ferrous rimming metal into an ingot mold and not substantially later than immediately after the conclusion of pouring placing in the upper portion only of the mold and fixedly positioning relatively to the mold a triangular plate of solid ferrous metal disposed with its apex downward which partially fuses into the molten metal and serves to move inclusions upwardly and outwardly and to reduce and limit the normal rimming action.

6. In a method of controlling the rimming of an ingot, the steps of pouring molten ferrous rimming metal into an ingot mold and not substantially later than immediately after the con clusion of pouring placing in the upper portion only of the mold and fixedly positioning relatively to the mold an insert of solid ferrous metal having a weight of from .2% to .5% of the weight 5 of the ingot which partially fuses into the molten metal and serves to move inclusions upwardly and outwardly and to reduce and limit thenormal The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 190,055 Maltby Apr. 24, 1877 284,004 Hainsworth Aug. 28, 1883 745,117

Rees Nov. 24, 1903 Number Number Name Date Hunt Apr.-4, 1905 Evans Sept. 17, 1907 York Nov. 28, 1916 Dornin Jan. 10, 1939 Belding Feb. 13, 1940 Sternberg Apr. 16, 1940 Francis et a1 Aug. 25, 1942 FOREIGN PATENTS Country Date Great Britain 1914 Germany Oct. 7, 1877 Germany Mar. 8, 1922 Austria Dec. 10, 1904 

